A conventional structure to fix an inflatable elastic motion body as shown in FIGS. 5 and 6 includes a main body (50), a base unit (60) and a ring frame (70). A fixing edge (51) is protrudingly formed at an edge of the bottom surface of the main body (50). A top surface of the base unit (60) is provided for the main body (50). The ring frame (70) is made by plastic materials and, a restricting slot (71) is recessely formed inside the ring frame (70) to fix and secure the fixing edge (51) of the main body (50) and the bottom surface of the base unit (60). The conventional structure is disadvantageous because (a) when the conventional inflatable elastic motion body is used, it bears great deal amount of pressure from a user, so the ring frame (70) made by plastic materials is easily to be bended or deformed, and the main body (50) cannot be securely fixed to the base unit (60); and (b) the base unit (60) are usually made by several boards connected with each other, but the structural strength is usually not strong enough, and it will adversely affect the durability of the entire structure for the inflatable elastic motion body. Therefore, there remains an improved and new structure to overcome the problems stated above.